Figure 1.
MMSET is involved in DNA repair. An ideogram of MMSET highlights the important functional domains of the protein, with arrows indicating the initiation of translation of the truncated forms, lacking Ser102, that result from translocation break points between the coding exons. After DNA damage, MMSET is phosphorylated on Ser102 by ATM and is recruited to sites of double-strand breaks by MDC1, where it methylates H4K20. Dimethylation of H4K20 recruits p53-binding protein (53BP1), a key transducer of the DNA-damage checkpoint signal. 53BP1 is required for p53 accumulation, G2/M checkpoint arrest, and the intra-S-phase checkpoint in response to ionizing radiation.
